Apparatus for cutting vegetation with incremental feeding of cutting filament

ABSTRACT

A vegetation cutting apparatus of the filament type comprising a cutter head including a spindle adapted to be rotatably driven, a keyway in the spindle extending axially of the spindle, and a key member carried by the spindle and slidably movable in the keyway. A clutch means is coaxially mounted on the spindle, and a filament storage spool is mounted on the spindle, the spool being carried by and lying radially outwardly of the clutch means, whereby the clutch means and the spool rotatably move as a unit. A spring means normally biases the key member into driving relation with the clutch means whereby normally the spindle rotatably drives the clutch means through the key member to rotatably drive the spool. A means such as a ground contact plunger operatively related to the key member, or, alternatively, an operating rod operatively related to the key member and actuated by a cable or the like, imparts axial movement to the key member along the keyway against the spring means to move the key member out of driving relation to the clutch means to permit relative rotation between the spool and the spindle and thus to permit an increment of the filament to be fed by centrifugal force from the spool.

FIELD OF THE INVENTION

This invention relates to an apparatus for cutting vegetation such asweeds, grass, or the like by means of a flexible, filamentous cuttingline or flail extending from a rotating head, and more particularly toan apparatus of this type having an improved arrangement for providingadditional increments of the flexible cutting filament to compensate forend portions of the filament which break off due to wear or for otherreasons.

DESCRIPTION OF THE PRIOR ART

Rotary weed cutters utilizing a filament type cutting element are wellknown in the art. Such filament-type weed and/or grass cutters usuallyutilize a monofilament plastic line which may be formed of nylon or thelike and which is wound onto a spool rotated by a rotary drive. Thefilament carried by the spool includes a free traveling end whichextends outwardly from the spool for a few inches and cuts vegetation inits path when the rotary cutter head is rotated at a relatively highspeed. Examples of filament-type apparatus for cutting vegetation suchas weeds or the like are shown by the following U.S. patents:

U.S. Pat. No. 3,928,911 Pittinger

U.S. Pat. No. 4,007,525 Utter

U.S. Pat. No. 4,077,191 Pittinger Sr. et al

U.S. Pat. No. 4,097,991 Proulx

U.S. Pat. No. 4,118,864 Pittinger Sr. et al

U.S. Pat. No. 4,134,204 Perdue

U.S. Pat. No. 4,136,446 Tripp

U.S. Pat. No. 4,137,694 Hopper

U.S. Pat. No. 4,138,810 Pittinger

U.S. Pat. No. 4,145,809 Proulx

U.S. Pat. No. 4,152,832 Akaike et al

U.S. Pat. No. 4,169,311 Evenson et al

U.S. Pat. No. 4,176,508 Baumann et al

U.S. Pat. No. 4,177,561 Ballas

U.S. Pat. No. 4,185,380 Hindman, Jr.

U.S. Pat. No. 4,185,381 Palmieri et al

U.S. Pat. No. 4,209,902 Moore et al

U.S. Pat. No. 4,235,068 Comer

U.S. Pat. No. 4,250,623 Pittinger et al

U.S. Pat. No. 4,281,505 Fuelling et al.

The following U.S. patents show filament-type cutting apparatus forcutting vegetation such as weeds or the like in which a plunger memberor the like carried by the rotating cutting head is bumped against theground surface to cause a declutching operation relative to the rotatingcutting head of the spool on which the filament is wound, whereby todeploy or pay out an additional increment of the cutting filament:

U.S. Pat. No. 4,161,820 Moore

U.S. Pat. No. 4,183,138 Mitchell et al

U.S. Pat. No. 4,203,212 Proulx

U.S. Pat. No. 4,236,309 Cayou

U.S. Pat. No. 4,259,782 Proulx

U.S. Pat. No. 4,274,201 Oberg et al

U.S. Pat. No. 4,209,902, Moore et al, shows an arrangement forincrementally feeding a cutting filament in which the incrementing feedof the filament is initiated by a lever member actuated by a controlcable.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide in avegetation cutting apparatus of the filament type a clutch arrangementfor providing an incremental feed of the cutting filament when required,including a sliding key which is movable to cause the filament spool tobe momentarily disconnected or declutched in rotational increments fromthe prime mover, whereby to permit incremental feeding of the cuttingfilament by centrifugal force.

It is a further object of the invention to provide a vegetation cuttingapparatus including a sliding key clutch which provides incrementalpositive rotational stepping of the filament spool with no impact from arotational ground coupling such as a ground contact plunger.

It is a further object of the invention to provide an incrementalfilament feed arrangement in an apparatus for cutting vegetation of thefilament type in which the ground contact plunger which is used toinitiate the incremental feeding of the filament is so related to theother components of the apparatus that it does not impart any rotationalforces to the sliding key clutch or to the filament spool which formpart of the vegetation cutting apparatus.

It is still a further object to provide a vegetation cutting apparatusof the filament type in which the centrifugal pulling forces on thefilament which is wound on the filament spool is the only force whichrotates and advances the spool and the clutch wheel associated with thefilament spool relative to the cutting head, to thereby minimize thedestructive forces on the incremental feeding mechanism.

It is a further object of the invention to provide a vegetation cuttingapparatus of the filament type including a ground contact plunger forinitiating the incremental feeding of the filament and in which allexcess ramming or rotational impact forces are isolated at and withinthe ground contact plunger regardless of the severity of the groundimpact.

It is a further object of the invention to provide a vegetation cuttingapparatus of the filament type which can be quickly disassembled andreassembled to permit replacement of the cover plate and the filamentspool when required.

It is a further object of the invention to provide a vegetation cuttingapparatus of the filament type which includes a flexible cord-likefilament which cuts weeds and light vegetation with a flail-like actionand in which the cutting apparatus additionally includes a cover platehaving saw teeth on the outer periphery thereof for the purpose ofcutting heavy growth of vegetation such as, for example, one-half inchtree off-shoots, with a sawing action.

It is still a further object of the invention to provide a vegetationcutting apparatus of the filament type which includes means for dampingvibrations which occur, particularly if the apparatus should vibrate ator pass through the resonant or natural vibrating frequency of therotating mass of the cutting apparatus.

It is still a further object of the invention to provide a vegetationcutting apparatus of the rotating filament type including a groundcontact plunger and a spring member biasing the ground contact plungerin a downward direction, and a cover plate which serves as a seat forthe normally lower end of the spool on which the filament is wound, thespring member which biases the ground contact plunger in a downwarddirection also serving to exert a constant pressure against the coverplate and against the end surfaces of the filament spool, whereby toprovide a dirt and mud seal while providing rotational friction to thespool and becoming a rotational shock absorber to the spool, to theclutch wheel which is keyed to the spool, and to the clutch key whichestablishes the driving connection between the clutch wheel and thedrive spindle.

BRIEF SUMMARY OF THE INVENTION

In achievement of these objectives, there is provided in accordance withembodiments of the invention a vegetation cutting appararus of thefilament type comprising a cutter head including a spindle adapted to berotatably driven, a keyway in said spindle extending axially of saidspindle, a key member carried by said spindle and slidably movable insaid keyway, a clutch means coaxially mounted on said spindle, a spoolmounted on said spindle for storing the filament, said spool beingcarried by and lying radially outwardly of said clutch means, wherebysaid clutch means and said spool rotatably move as a unit, meansnormally biasing said key member into driving engagement with saidclutch means whereby normally said spindle rotatably drives said clutchmeans through said key member to thereby rotatably drive said spool,means for imparting axial movement to said key member along said keywayagainst said biasing means whereby to move said key member out ofdriving relation with respect to said clutch means, and thus whereby totransitorily interrupt the rotatable drive connection from said spindleto said spool through said clutch means, whereby to permit relativerotation between said spool and said spindle, and thus whereby to permitan increment of said filament to be fed by centrifugal force from saidspool. The means for imparting axial movement to said key member may bea ground contact plunger carried by the normally lower end of the cutterhead and operatively related to the key member whereby to impart axialmovement to the key member. Alternatively, the means for imparting axialmovement to the key member may be an operating rod operatively relatedto the key member and adapted to be actuated by a cable or the like toaxially move the key member.

Further objects and advantages of the invention will become apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in perspective of the vegetation cutting apparatus ofthe invention in operation;

FIG. 2 is a view in perspective showing how the apparatus of FIG. 1 maybe attached to a drive mechanism;

FIG. 3 is an exploded view of the vegetation cutting apparatus;

FIG. 4 is a top elevation view showing how the filament spins out duringrotation of the cutting head, and also showing how the filament ispositioned with respect to the pins;

FIG. 5 is a side elevation view of the cutting apparatus of FIG. 1;

FIG. 6 is a bottom view showing the locking and unlocking arrangement;

FIG. 7 is an exploded view showing the first step in the disassemblyoperation;

FIG. 8 is an exploded view showing the second step in the disassemblyoperation;

FIG. 9 is an exploded view showing the third step in the disassemblyoperation.

FIG. 10 is an exploded view showing the fourth and final step in thedisassembly operation;

FIGS. 11, 12 and 13 are sectional views taken on lines 11,11, 12,12 and13,13 respectively through the key element shown in FIG. 10.

FIG. 14 is a view taken in section along line 14--14 of FIG. 4 of thepreferred embodiment, showing the ground engaging plunger in its fullyextended outward position;

FIG. 15 is a fragmentary view in cross section similar to FIG. 14 alongline 14--14 of FIG. 4 showing the effect of the ground-engaging plungerbeing struck or bumped on the ground surface causing the sliding key tomove into a different clutch cavity;

FIG. 16 is a view in horizontal section taken along line 16--16 of FIG.14 showing how the upper and lower clutch cavities are positioned withrespect to each other; and further showing the position of the slidingkey in driving engagement with the upper clutch cavity before the groundcontact plunger is "bumped" or struck against the ground, at which timethe sliding key will move into driving engagement with the lower clutchcavity;

FIG. 17 is a view of an alternative embodiment along a cross sectionsimilar to those used in FIGS. 14 and 15, in which the movement of thesliding key is obtained by movement of a cable member or the like whichis connected to the sliding key;

FIG. 18 is a bottom view of the alternative embodiment of FIG. 17;

FIG. 19 is a view showing a flyball governor which is used inconjunction with the alternative embodiment of FIG. 17; and

FIG. 20 is an enlarged view of the clutch mechanism employed in thealternative embodiments of FIGS. 17-19, inclusive.

FIG. 21 is a sectional view similar to FIG. 14 but showing the cutterhead with a modified clutch retainer ring;

FIG. 22 is like FIG. 15 but showing the cutter head with the modifiedclutch retainer ring of FIG. 21;

FIG. 23 is an enlarged partial side elevational view of the clutch keyincluded in the embodiment of FIG. 17 showing the curved surfaces of theupper and lower clutch key elements;

FIG. 24 is an end view of the clutch key shown in FIG. 23.

FIG. 25 is a perspective view similar to FIG. 2 but showing the cutterhead of FIGS. 17 and 18 substituted for the cutter head of FIG. 2 andfurther showing the clutch key operating mechanism of FIG. 19 mounted ontop of drive shaft housing 12'.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in FIG. 1, the filament type rotary cutter head generallyindicated at 10 may be supported from a hollow tube member 12 connectedat its upper end to a handle 14 which is held by the operator. Aflexible drive shaft may pass through hollow tube 12 and may beconnected to the drive spindle 16 of the rotary cutter as will beexplained in more detail hereinafter. The opposite end of the flexibleshaft is connected to the output of a suitable prime mover such as, forexample, a small gasoline engine 18 mounted on the back of the operator.

Cutter head 10 comprises a centrally located spindle 16 which isprovided intermediate the height thereof, but substantially closer tothe upper end of the spindle than to the lower end thereof, with acircular flange 19.

The cutter head includes a hollow cap member generally indicated at 21comprising an upper disc 22 provided with a downwardly extending annularflange 22A around its outer periphery; and a lower disc 24 provided withan upwardly extending annular flange 24A around its outer periphery. Thetwo annular flanges 22A and 24A of the respective discs 22 and 24 are inmating abutting relation to each other to circumferentially bound thehollow interior of cap 21. Each of the respective discs 22 and 24 isprovided with a corresponding centrally located aperture, and a centralhub member 26 lying within hollow cap 21 extends in circumferentiallybounding relation to the respective apertures of the two discs 22 and24, hub member 26 extending in an axial direction between the lowersurface of upper disc member 22 and the upper surface of lower discmember 24, with respect to the views shown in FIGS. 14 and 15.

Hollow cap member 21 is coaxially positioned about the upper portion ofspindle 16, with the lower surface of lower disc 24 seating of the uppersurface of flange 19 on spindle 16. The portion of spindle 16 lyingabove flange 19 of the spindle is externally threaded as indicated at28, and an internally threaded nut 30 is secured on threaded portion ofspindle 16 which projects above the upper surface of the upper discmember 24, whereby to secure cap 21 in assembled relation with respectto the upper end of spindle 16.

The upper end of spindle 16 is provided with a countersunk recess 32 inthe face thereof, and a screw-threaded passage 34 extends downwardlyfrom the lower end of countersunk opening 32. A suitable screw-threadedmember D carried by a flexible drive shaft (not shown) may be engagedwith screw-threaded passage 34 in the upper end of spindle 16 whereby topermit driving of spindle 16, and hence, of cutter head 10 by means of asuitable prime mover such as a gasoline engine or the like.

The entire portion of the height of spindle 16 which lies beneath hollowcap 21 including circular flange 19 of spindle 16 is provided with anaxially extending recess or slot 23 extending radially inwardly from theouter peripheral surface of spindle 16 and of flange 19 and whichdefines a keyway to receive a slidably movable key 38 to be described inmore detail, which cooperates with a clutch wheel 40, also to bedescribed, to permit placing filament spool 80, to be described,selectively into or out of driven relation with respect to spindle 16.

Each of the respective discs 22, 24 of hollow cap member 21 is providedwith four equally circumferentially spaced apertures each indicated at42 which may be spaced at 90° intervals around the periphery of capmember 21, the apertures 42 being located contiguous but spaced radiallyinwardly a short distance of the outer periphery of cap member 21.Corresponding apertures 42 of the respective axially spaced discs 22, 24are in vertical alignment with each other.

A corresponding post 43 is press fitted in each set of aligned upper andlower apertures in the respective upper and lower discs 22 and 24 of capmember 21. The upper ends of the respective posts 43 project a shortdistance above the upper surface of upper disc. 22. The major portion ofthe height of the respective posts 43 extends beneath lower disc 24, anda cover plate 44 to be described is mounted on the lower ends of theposts 43.

As seen in the views of FIGS. 2, 4, and 5, the vertical posts 43 serveas abutments which limit the circumferential swinging movement of theradially outwardly projecting portions of the filaments.

As will be described in more detail hereinafter, cover plate 44 may beprovided with saw teeth 46 on the outer periphery thereof for thepurpose of cutting thicker vegetation than would normally be cut by thefilament type cutter.

As best seen in the view of FIGS. 14 and 17, each of the posts 43 hasmounted on the portion of the respective post 43 which lies within thechamber bounded by upper and lower discs 22 and 24 a vibration dampingmeans in the form of a counterweight 48 such as a metal washer. Thewashers 48 are fitted loosely on the respective posts 43 to provide asubstantial clearance between the outer periphery of the respectiveposts 43 and the inner periphery of the central apertures of the washerswhich define the vibration damping counterweights.

The vibration damping counterweights 48 defined by the metal washersfitted loosely on the posts 43 can be sized or tuned to respond to asmall degree of imbalance or rotational vibration of the cutter head. Ifthere is no imbalance or vibration present, then centrifugal force willmerely force the vibration damper counterweights outwardly during thehigh speed rotation of the cutter head and the rotating system willremain in a steady state condition.

It is difficult for the operator of the rotating cutter head to maintaina constant or exact speed of rotation with varying density of vegetationand unit load, and therefore during the operation of the cutter head,the cutter head rotary speed may be such that it may transitorily passthrough the natural vibrating frequency of the rotating mass. When thisoccurs, the vibration damping counterweights will dynamically reactagainst the temporary natural vibrating frequency by momentarilybecoming offset or eccentric with respect to the posts 43 on which theyare mounted during one-half of a revolution of the cutter head and thenexerting an added force on the posts during the next half revolution.However, until a vibration is induced or exists from external orinternal sources the vibration damping counterweights remain dormant orinactive. The external forces which may set up vibrations may beexternal turning fork type of momentary impact loading or filamentimbalance; while vibrations may also be set up by internal naturalvibration frequency.

As best seen in the view of FIGS. 3 and 10, the sliding key member 38 isprovided with three laterally extending key elements respectivelyindicated at 38A, 38B and 38C which are in spaced relation to each otherlengthwise of key member 38. Key elements 38A and 38B are respectivelyadapted to cooperate with the upper and lower clutch cavities 40A, and40B, of clutch 40, as will be described in more detail hereinafter. Keyelement 38C is engaged in annular groove 72 of ground contact plunger66, to be described, whereby vertical movement of ground contact plunger66 due to being "bumped" onto the ground causes vertical movement ofsliding key 38 whereby to shift sliding key 38 out of driving engagementwith upper clutch cavity 40A and into driving engagement with lowerclutch cavity 40B, to cause incremental feeding of the cutting filamentas will be described in more detail hereinafter.

Coaxially positioned about spindle 16 and sliding key 38 is a clutchwheel 40. Clutch wheel 40 is a hollow cylindrical member havingintermediate of its axial height a radially inwardly extending andaxially extending annular wall 41. Clutch wheel 40 is provided aroundthe entire internal periphery thereof with a plurality of closely spacedupper clutch wheel cavities 40A lying above annular wall 41; and clutchwheel 40 is also provided around its entire inner periphery with asecond set of closely spaced lower clutch wheel cavities 40B which liebelow annular wall 41 of the clutch wheel and thus below upper clutchwheel cavities 40A.

During normal operation of cutter head 10, key element 38A of slidingkey member 38 is engaged in driving relation with one of the upperclutch wheel cavities 40A due to the downward biasing force imparted toground contact plunger 66 and to sliding key 38 by axial biasing spring67. However, as will be explained in more detail hereinafter, whenground contact plunger 66 is "bumped" against the ground surface, keymember 38 is moved axially upwardly to disengage key element 38A fromone of the upper clutch cavities 40A and to engage key element 38B indriving relation with one of the lower clutch cavities 40B.

Clutch wheel 40 is provided with a pair of diametrically opposite keyelements each indicated at 45 which in the illustrated embodiment extendfor the entire axial height of clutch wheel 40. Key elements 45 engagecorresponding slots 86 in the inner periphery of the annular filamentspool 80 whereby to detachably interlockingly engage clutch wheel 40with filament spool 80 so that filament spool 80 rotates with clutchwheel 40 when clutch wheel 40 is being driven by drive spindle 16through sliding key member 38.

As best seen in the view of FIG. 16, upper clutch cavities 40A which areshown in full line in FIG. 16 are offset by one-half pitch from lowerclutch cavities 40B which are shown in dotted line in FIG. 16. Thisone-half pitch offset relation of the upper cavities with respect to thelower cavities permits the cutter head 10 to be operated in either aclockwise or in a counterclockwise direction.

In the cross-sectional view of FIG. 16, key element 38A of sliding key38 which is keyed to spindle 16 is assumed to be rotating in a clockwisedirection, as viewed in FIG. 16, along with spindle 16, causing theleading edge of key element 38A, with respect to the direction ofrotation, to engage the leading edge 40A-1 of upper clutch cavity 40A,whereby to drive clutch wheel 40, and hence filament spool 80 (to bedescribed) which is keyed to clutch wheel 40, in a clockwise directionas viewed in FIG. 16. Similarly, when sliding key 40 is moved upwardlyto move key 40 out of engagement with upper clutch cavity 40A and into alower clutch cavity 40B, the leading edge of key element 38B, withrespect to the direction of rotation, will drivingly engage the leadingedge 40B-1 of a lower clutch cavity 40B to drive clutch wheel 40, andhence to drive filament spool 80 keyed thereto, in a clockwise directionas viewed in FIG. 14.

It is important to note that before the upper clutch key element 38Amoves out of engagement with the leading edge 40A-1 of the upper clutchcavity 40A in which key element 38A is seated, the lower clutch keyelement 38B will move into the lower clutch cavity 40B below the upperclutch cavity 40A. However, because the lower clutch cavities 40B areoffset by one-half pitch from the upper clutch cavities, the lowerclutch key element 38B moves up into the lower clutch cavity adjacentthe trailing edge 40B-2 thereof. As soon as the clutch key 38 slidesupward for enough for the upper clutch key element 38A to disengage theupper clutch cavity 40A, continued clockwise rotation of the spindle 16will move the clutch key element 38B forward within the lower clutchcavity 40B until it strikes the leading edge 40B-1 of the lower clutchcavity. The clutch wheel 40 and filament spool 80, once the upper clutchkey element 38A disengages the leading edge 40A-1 of the upper clutchcavity 40A, will lag behind the rotating spindle 16 and key 38 until thelower clutch key element 38B moves from adjacent the trailing edge 40B-2to engage the leading edge 40B-1 of the lower clutch cavity 40B whencepositive drive of the clutch wheel 40 and filament spool 80 isre-established through engagement ot the lower key element 40B with theleading edge 40B-1 of the lower clutch cavity.

The hollow cap member 21 and the posts 43 will advance clockwise withthe spindle 16 relative to the clutch wheel 40 and the filament spool 80because the cap member 21 is secured to the spindle. Centrifugal forceacting upon the filament ends, unwinds the filaments from the spool 80until the filaments again bear upon the posts 43. The filaments are thusadvanced one-half increment.

After the bumping of the plunger 66 upon the ground has forced the key38 up in the manner just described, the spring 67 which has beencompressed by the bumping action of the plunger 66 against the ground,will force the plunger 66 and key 38 downwardly to the fully extendedposition shown in FIG. 14. Downward motion of the key 38 will cause theupper key element 38A to enter the next succeeding upper clutch cavity40A' adjacent the trailing edge 40A'-2 thereof, and the lower keyelement 38B will move out of the lower clutch cavity 40B. Once the lowerkey element 38B has disengaged the lower clutch cavity, the spindle 16and key 38 will advance relative to the lagging clutch wheel 40 andspool 80 until the leading edge of the upper key element 38A engages theleading edge 40A'-1 of the upper clutch cavity 40A'. The hollow cap 21and posts 43 secured therein will thus advance with the spindle 16 andspool 80 for another half increment and the filaments 88A and 88B willunwind from the spool 80 until they again bear upon the posts 43. Onefull increment of feed of the filaments 88A and 88B is therebycompleted.

It is within the scope of this invention to provide a filament cuttingelement or elements (not shown) within the cutter housing H atappropriate locations to sever frayed ends of the filaments 88. U.S.Pat. No. 4,047,455 illustrates the use of cutter elements to sharpenfilaments of a filament-type vegetable trimmer.

An annular retaining ring 52 having the same outer diameter as clutchwheel 40 (not including the dimension added by keys 45 on the clutchwheel) seats against the under surface of clutch wheel 40.

A spring-biased detent assembly generally indicated at 53 is providedcontiguous the lower portion of spindle shaft 16, comprising a detentplunger 54 which is received in a laterally-extending cavity 56 bestseen in FIGS. 14 and 15 which opens inwardly from the outer periphery ofthe lower portion of spindle shaft 16. Cavity 56 extends in a directionperpendicular to the vertical axis of spindle shaft 16. A spring member58 is received in cavity 56 between the inner end of the detent plunger54 and the inner end of cavity 56 to normally bias plunger 54 in alaterally outward direction to permit the smaller diameter laterallyouter end portion 54B of plunger 54 to project through the end opening60 of cavity 56. Outlet opening 60 is of smaller diameter than theinternal diameter of cavity 56 and the inner end portion 54A of plunger54 is of greater diameter than that of outlet opening 60, whereby topermit only the reduced diameter outer end portion 54A of plunger 54 toextend outwardly through outlet opening 60, and whereby to retain innerportion 54A of plunger 54 in cavity 56.

A hollow cylindrical retaining sleeve 62 seats on the surface ofretaining ring 52. Retaining sleeve 62 is open at both opposite endsthereof but is provided at the normally upper end thereof as viewed inFIGS. 14 and 15 with a radially inwardly extending flange 64 which makesthe opening at the upper end of sleeve 62 of smaller diameter than theopening at the lower end thereof.

Retaining sleeve 62 receives in the upper portion of the hollow interiorthereof a spiral spring member 67 which is for the purpose of biasingground contact plunger 66 in an axially downward direction. Spring 67 isinserted into retaining sleeve 62 from the normally lower end of sleeve62, the normally upper end of spring 67 bearing against the under orinner surface of radially inwardly extending flange 64 at the upper endof sleeve 62 as viewed in FIGS. 14 and 15. Cylindrical retaining sleeve62 is provided with an aperture 63 in the cylindrical wall thereofcontiguous the lower portion of sleeve 62, and ground contact plunger 66is provided with a vertical-slot-like aperture 70. The apertures 63 and70 of sleeve 62 and of ground contact plunger 66, respectively, arealigned with each other when it is desired to gain access to detentplunger 54 of spindle 16 during the assembly or disassembly operations,as will be described hereinafter.

As best seen in the views of FIGS. 3, 14, and 15, the ground contactplunger generally indicated at 66 comprises a cylindrical body portion66A and a lower end portion of partially spherical shape 66B. Groundcontact plunger 66 has a hollow interior which is bounded at the upperend of cylindrical body portion 66A thereof by an annular bevelled lip69 which bounds the entrance to the upper end of the hollow interior ofground contact plunger 66.

A short distance below the upper opening of ground contact plunger 66and beneath the bevelled lip 69, an annular groove 72 is provided in thecylindrical inner wall of plunger 66 to receive key element 38C ofsliding key member 38, whereby any vertical movement of ground contactplunger 66, such as movement caused by "bumping" the ground contactplunger 66 on the ground, is communicated to sliding key member 38.

The lower surface of annular groove 72 is bounded or defined by theupper surface 73A of annular rib 73 within the hollow interior ofplunger 66. The under or lower surface 73B of annular rib 73 bounds asecond or lower annular groove 74 beneath the first or upper annulargroove 72 and of substantially greater axial height than upper annulargroove 72. Lower annular groove 74 receives the laterally projecting endof detent plunger 54, whereby to interlock ground contact plunger 66with spindle 66 when spring-biased plunger 54 is in its normallyoutwardly projected position as seen in FIGS. 14 and 15.

The interlocked engagement of ground contact plunger 66 with spindle 16by means of the engagement of laterally-projecting plunger 54 carried byspindle 16 with annular groove 74 of plunger 66, and also the mountingof key element 38C in annular groove 72 of ground contact plunger 66both have the effect of permitting ground contact plunger 66 to slip orrotate independently of spindle shaft 16 if any severe rotational impactforces or movements are imparted to ground contact plunger 66 such asmight be caused by impacts of the plunger with the ground surface. Therelative rotation capability of ground contact plunger 66 with respectto sliding key 38 and clutch wheel 40 prevents the transmission of suchrotational impact forces from ground contact plunger 66 to sliding key38 and to clutch wheel 40. However, in the absence of such rotationalimpact forces on plunger 66, ground contact plunger 55 normally rotateswith spindle 16 due to frictional drag between key clutch element 38Ccarried by spindle 16 and receivable in groove 72 of ground contactplunger 66.

Upward movement imparted to ground contact plunger 66 relative to therest of the assembly, as when ground contact plunger 66 is bumpedagainst the ground surface, transmit the upward move-ment of groundcontact plunger 66 to slidable key 38, whereby to move key 38 out ofengagement with one of the upper clutch cavities 40A and into engagementwith one of the lower cavities 40B, as has been previously described.

Biasing spring 67 is received in the cavity of cylindrical retainingsleeve 62 above ground contact plunger 66 and urges plunger 66 downagainst spring biased detent plunger 54 carried by spindle 16. Morespecifically, as seen in FIG. 14, biasing spring 67 normally urges thelower surface 73B of internal annular rib 73 which bounds the annulargrooves 72 and 74 down against the upper surface of spring biased detentplunger 54. The cooperative relationship of the parts just describedlimits the upward movement of ground contact plunger 66 against thelower end of drive spindle 16 to a predetermined vertical movement asdefined by the axial height of annular groove 74 in plunger 16, therebysubstantially preventing any excessive vertical impact loading beingtransmitted from ground contact plunger 66 to spindle shaft 16 or tosliding key 38.

In summary, the mounting arrangement of key element 38C in annulargroove 72 of ground contact plunger 66, and the relationship of spindleshaft 16, axial biasing spring 67, and ground contact plunger 66 allcooperate to prevent the transmission of excessive rotational andvertical impact forces from ground contact plunger 66 to sliding key 38or to clutch wheel 40. All excessive vertical impact or rotationalimpact forces are isolated within ground contact plunger 66 and are nottransmitted to sliding key 38 or to clutch wheel 40.

The filament reel generally indicated at 80 may be generally similar tothe filament reel shown in FIGS. 10-12, inclusive, or U.S. Pat. No.4,250,623 issued on Feb. 17, 1981, to Charles B. Pittinger and CynthiaA. Pittinger. Spool 80 comprises a plurality of annular discs 82 fixedto a central cylindrical hub. In the illustrated embodiment, thefilament reel 80 comprises five vertically spaced annular discs 82 lyingin parallel planes to define channels 85 between adjacent discs 82. Twoseparate lengths of filament 88 may be wound on spool 80, including afilament 88A which is wound in the upper group of channels 85 withrespect to the view shown in FIG. 3 of the present application and asecond filament 88B which is wound in the lower group of channels withrespect to the view shown in FIG. 3. Thus, the outer end portions of thetwo separate filaments 88A and 88B are shown extending radiallyoutwardly of spool 80, the inner ends of each of the respectivefilaments being received within the interior of one of the correspondingchannels 85. The filaments may typically be a suitable monofilamentplastic line of nylon or other suitable material.

Each filament 88 is wound in superposed layers or windings within itscorresponding channels 85. Each channel has a width as defined by theaxial or vertical spacing between adjacent annular discs, only slightlygreater than the diameter of the filament which is wound therein, thuspreventing successive turns of the filament from being jammed side byside in the channel. The depth of each channel in a radial direction issufficient to receive a number of superposed turns of the filament 88.

As best seen in the view of FIG. 3 of the present patent application,the two lowermost annular discs are provided with radial slots 80Aextending radially inwardly from the circumference of the annular discsfor a substantial portion of the radial dimension of the respectivediscs. The slots 80A lie in a common vertical plane with each other.Also, the upper three annular discs with respect to the view shown inFIG. 3 of the present application are provided with similar radial slotsbut diametrically opposite the location of the radial slots 80A. Theslots such as 80A permit the turns of the filament to be crossed overfrom one channel to the next adjacent channel.

After the clutch wheel 40, retaining ring 52, retaining sleeve 62, axialbiasing spring 67, and ground contact plunger 66 have all been assembledonto spindle shaft 16 in the order shown in the exploded view of FIG. 3,the filament spool 80 may then be positioned coaxially about clutchwheel 40, the filament spool being interlocked in driven relation to theclutch wheel by engagement of two diametrically opposite key ways 86 onthe inner periphery of spool hub 80 with respect to diametricallyopposite keys 45 carried by the outer peripheral surface of clutch wheel40.

The final assembly step is to coaxially position the cover plate 44about the outer periphery of retaining sleeve 62, the plurality ofcircumferentially spaced notches 90 on the inner periphery of the coverplate being engaged with the similarly circumferentially spaced lugs orabutments 91 which extend from the outer peripheral surface of retainingsleeve 62 in the upper portion of sleeve 62.

To retain the parts in the assembled position, the cylindrical retainingsleeve 62 may be pulled axially outwardly against the force of thebiasing spring 67 and the cylindrical sleeve 62 is then rotated so thatthe lugs 91 of the cylindrical sleeve 62 are not in registry with thenotches 90 in the cover plate, as best seen in the view of FIG. 6. Whenthe cylindrical sleeve has been rotated to the "Locked" position, it isreleased, permitting the force of biasing spring 67 to draw the endsurface of the cylindrical sleeve up tightly against the abuttingsurface of the cover plate 44. Circumferentially spaced lock notches 92,of lesser depth than the notches 90, are spaced evenly between thenotches 90 on the inner periphery of the cover plate 44. They receivethe reduced upper ends 93 of the lugs 91 in the lock position of thesleeve 62 to secure the sleeve against rotation until the sleeve isagain deliberately pulled out and rotated to align the lugs 91 withnotches 90 for the purpose of disassembly.

In the assembled cutter head, as just described, the biasing spring 67which biases the ground contact plunger and the sliding clutch key 38downwardly maintains a constant pressure against the cover plate 44, andthe end surfaces of the filament spool 80, thereby providing a dirt andmud seal while providing rotational friction on the filament spool 80,spring 67 additionally becomes a rotational shock absorber to the clutchwheel 40 and clutch key 38. The downward biasing force of spring 67 alsocompensates for manufacturing tolerances of component parts of theassembly, while simultaneously yielding during clutching and spoolfilament incremental feeding or rotational advancement.

Cover plate 44 may be provided on the exterior periphery thereof withsaw teeth 46. The saw teeth 46 may be used for cutting growth or treeoffshoots, such as 1/2-inch tree offshoots. When the cover plate withthe saw teeth thereon is being used for cutting growth as justdescribed, the filaments flex out of the way, permitting the cuttingplate saw teeth to perform the cutting operation.

The saw teeth 46 may be of various types such as coarse, fine, etc. Itis also within the scope of the invention to use a cover plate 44 havinga smooth outer circumference without having any saw teeth thereon.

When it is desired or necessary to replace the filaments or filamentreel, this may be easily done without the necessity of disassembling thecylindrical sleeve 62, the ground contact plunger 66, or the slidingclutch key 38 in the following manner:

The cylindrical retaining sleeve 62 is pulled out axially against thepressure of biasing spring 67 and is rotated to align lugs 91 on sleeve62 with slots 90 in cover plate 44, as best seen in the views of FIGS.3, 6, 7 and 8. The cover plate may then be pulled over the four mountingposts 43 and removed from the assembly as seen in the disassembled viewof FIG. 7 which represents the first step in the disassembly operation.

With the cover plate 44 removed, the filament spool 80 may then beremoved from the assembly by simply lifting it upwardly from its alreadyassembled position by sliding the slots or keyways 86 in the innerperiphery of the spool 80 up over the lugs 91 on the outer periphery ofthe threaded sleeve 62. The parts will then be as shown in the explodedview of FIG. 8 which represents the second step in the disassemblyoperation. Thus, it will be seen from the foregoing that the cutter headassembly is so constructed as to permit easy disassembly of the filamentreel 80 for replacement or repair if required.

If it is desired to further disassemble the cutter head to gain accessto the other parts of the assembly, such as the spindle 16, the slidingkey 38, or the clutch wheel 40, for example, the following additionaldisassembly steps are performed:

As seen in FIG. 8, the cylindrical sleeve 62 is rotated to align theaperture 63 in the sleeve 62 with the aperture 70 in the side wall ofthe ground contact plunger 66, and then rotating the cylindrical sleeve62 and ground contact plunger 66 with their respective apertures 63 and70 aligned with each other until these apertures are aligned with thespring-pressed detent plunger 54 (see FIG. 14). When this has been done,the end of a nail or the like may then be inserted in the alignedapertures in the sleeve 62 and in the ground contact plunger 66. Thedetent plunger 54 may then be pushed inwardly against the biasing forceof lateral biasing spring 58 to thereby retract plunger 54 from itsengagement with the annular groove 74 of ground contact plunger 66,thereby permitting cylindrical sleeve 62 and ground contact plunger 66to be removed from spindle 16. The sliding key 38 and the clutch wheel40 will move outwardly with the cylindrical sleeve 62 and the groundcontact plunger 66 until the key element 38C of sliding key 38 isdisengaged from the internal annular groove 74 of ground contact plunger66. Clutch wheel 40 can be removed from spindle 16 by again depressingthe detent plunger 54 to permit clutch wheel 40 to slide off the end ofthe spindle 16. The operating parts of the cutter head will then becompletely disassembled.

There is shown in the view of FIG. 17 a modified embodiment of theinvention in which sliding movement is imparted to the sliding keymember by a cable or the like, rather than by use of a ground contactplunger which is "bumped", as previously described.

The cutter head generally indicated at 100 in FIGS. 17 and 18 comprisesa spindle member 116 having mounted thereon a hollow cap member 121which is generally similar to the hollow cap member 21 described inconnection with the embodiment of FIGS. 1-16, inclusive. The upper endof spindle 116 is externally threaded as indicated at 128 and aninternally threaded nut member 130 threadedly engages the externalthread 128 to hold cap member 121 in position. The cap member 121 isprovided with apertures 142 for receiving posts 143, and counterweights148 are mounted on the upper portion of the respective posts 143 withinthe interior of hollow cap 121, all in a manner similar to theembodiment of FIGS. 1-16, inclusive. The outer wall of spindle 116 isrecessed to permit sliding movement of a key member 138 which cooperateswith a clutch wheel 140 similar to that described in the embodiment ofFIGS. 1-16, inclusive; and a filament reel 180 is keyed to and rotateswith the clutch wheel 140, all in a manner similar to that previouslydescribed in the embodiment of FIGS. 1-16, inclusive.

The modified embodiment of FIGS. 17 and 18 differs from the previouslydescribed embodiment in that there is no ground contact plunger 66, noaxial biasing spring, no lateral detent subassembly, and no retainingsleeve 62, such as those of the previously described embodiment. Slidingmotion is imparted to the sliding key member 138 by means of anoperating rod or member 139 which is connected to the sliding key member138 and extends vertically upwardly through a hollow vertical passagelying along the central vertical axis of spindle 116. The upper end ofthe rod or extension 139 projects above the upper surface of spindle 116where it may be connected to a suitable actuating member such as a cableor the like which may be actuated to raise or lower key member 138 tomove the upper key element 138A out of engagement with an upper clutchcavity 140A and to cause the lower key element 138B to move intoengagement with the lower clutch cavity 140B, in a manner generallysimilar to the relationship of the key elements 38A, 38B to the clutchcavities 40A, 40B of the previously described embodiment of FIGS. 1-16,inclusive.

The modified embodiment shown in FIGS. 17 and 18 is suitable for usewith a cutter head intended for operation in wet marsh ground or thelike, where it would be impractical to impart movement to the cutterhead by a ground contact plunger such as that described in FIGS. 1-16,inclusive.

There is shown in FIG. 19 a flyball governor arrangement which may beused to impart movement to the sliding key 138 of the cutter head 100(FIG. 17) to cause incremental feeding of the filament. Thus, theflyball governor arrangement in FIG. 19 is generally indicated at 125and includes a collar member 127 which is connected to the sliding keymember 138 through an operating rod 139. The collar member 127 includesa centrally located recess 127A defined by a conical wall surface 129which tapers in an inward and upward direction to meet the flat uppersurface 131 of the recess or cavity. The upper end of the rod member 139is secured to the flat upper surface of the cavity in the tapered collar127. Governor flyballs 132 are positioned in the space between rodmember 139 and the tapered surface 129. A biasing spring 134 bearsagainst the top surface of the collar 127.

The fly ball governor 125 also includes a housing 151 comprising a baseplate 151' and a dome-shaped cover 152 which has an inwardly deformedhub portion 153 which fits inside the upper end of the coil spring 134and provides bearing support therefor. The base plate 151 may beremovably joined to the domed cover 152 by a screw thread connection orby other suitable means. The fly balls 132 are supported beneath thecollar 127 by a circular plate 154 which normally rests in a planeperpendicular to the rod 134 against an annular stop ring 155 fixedinside of the housing 151. The plate 154 has a central hole 156 thereinthrough which the rod 139 slides loosely.

Normally the coil spring 134 acting upon the top of the collar 127forces the collar 127 downwardly to the position shown in FIG. 19 andthe clutch key 138 which is actuated by the clutch key actuating rod 139will be in the position shown in FIG. 17. When the speed of rotation ofthe cutter head 100 reaches a predetermined speed, at which centrifugalforce acting upon the flyballs 132 in the cavity 127A is sufficient toforce the flyballs to move outwardly, the outward movement of theflyballs acting against the conical surface 129 of the collar 127 willlift the collar 127 against the bias of spring 134. The clutch keyactuating rod 139 attached to collar 127 will be raised, thereby liftingthe clutch key 138. Lifting clutch key 138 disengages the upper clutchkey element 138A from the upper clutch cavity 140A in which it has beenengaged, and engages the lower clutch key element 138B with a lowerclutch key cavity 140B which is angularly offset from the upper clutchkey cavity so that the clutch ring 138 and the filament reel 180, whichis keyed thereto by posts 141, will shift angularly relative to the restof the cutter head 100. This angular shifting of the reel 180 relativeto the cutter head allows the filaments wound on the reel 180 to feedoutwardly an incremental length.

As further shown in FIG. 19, a lever 157 having oppositely curved ends157a and 157b is pivotally mounted on a bracket 158 fixed outside of thehousing cover 152 by a pivot pin 159. The curved end 157a of lever 157extends through a slot 160 in the housing cover 152 adjacent base plate151 and is secured to the peripheral edge of the circular plate 154 bysuitable means such as by welding. The application of a counterclockwiseforce (indicated by arrow 165) to the lever 157, as by a pull cord 164attached to the end 157b of the lever, or by a mass weight 161 attachedto an arm 162 extending outwardly from and attached to the lug 163through which lever 157 is pivoted to bracket 158 will lift the circularplate 154. Lifting of plate 154 lifts the balls 132 with resultinglifting of the collar member 127 and rod 139 which in turn lifts theclutch key 138 of the cutter head 100.

FIG. 25 shows the cutter head 100 of FIGS. 17 and 18 mounted on the bodysupported cutter drive mechanism similar to the cutter drive mechanismillustrated in FIGS. 1 and 2. The clutch key operating mechanism of FIG.19 is shown mounted on top of the vertical drive shaft housing 12'. Thedrive shaft D (see FIG. 17) extends into the housing 12' and isoperatively connected with a drive shaft extending through the tube 12from engine 18 by suitable drive means, such as gearing. It has an axialbore as shown in FIG. 17 for passage of the clutch key operating rod 139therethrough. A hole (not shown) is provided through the top of casing12' so that the clutch key operating rod 139 passes through casing 12'into the flyball governor casing 151 in the manner shown in FIG. 19. Theflyball governor casing 151 is suitably secured on top of casing 12' byattaching the base plate 151' to the top of casing 12' in any suitablemanner as by welding or by use of removable screw fasteners or the like.

While FIG. 19 shows multiple clutch key operating means provided in oneassembly, it is within the scope of this invention that any one, anytwo, or all of the operating means shown in FIG. 19 can be provided foractuating the clutch key 138.

The pull cord and lever as shown in FIG. 19 are for manual actuation ofthe clutch key whenever the operator wants to renew the cutting portionof the filaments by feeding out incremental lengths of filaments fromthe spool 180.

The flyball governor 125 is used in situations where automaticincremental feed of the filaments in response to an increased speed ofrotation of the cutter head 100 as sensed by the governor 125 isdesired.

The mass weight 161 is provided for actuating the clutch key 138 inresponse to a sudden jerking movement of the cutter head by movement ofthe handle 14 in a vertical direction causing the mass weight 161 andarm 162 to move downward about its pivot 159 and lifting the plate 154,balls 132, collar 127 and rod 139 against the bias of spring 134.

Instead of using the cutter head 100 of this invention in conjunctionwith the body carried support arm 12 as in FIG. 25, the cutter head canbe attached to the drive shaft of a lawn mower of the gasoline engine,or electric motor driven type which has a wheeled chassis with driveshaft extending downwardly beneath the chasis. Provision would be madefor access to the clutch key operating rod so that any one of the threeclutch key operating means, or any combination thereof, shown in FIG.19, could be used to reciprocate the clutch key operating rod 139. Theuse of a mass weight operator would be especially suitable for use witha four-wheel chassis mounted cutter head so that bumping of the chasisby lifting the front wheels and then bumping them on the ground with asudden movement will cause the mass weight of FIG. 19 to lift theactuating rod 139 against the bias of spring 134, thus actuating key 138of head 100 to cause incremental feed of filaments.

FIGS. 21 and 22 show a modified cutter head 10' corresponding to thecutter head 10 disclosed in FIGS. 1-16, with the only exception that theclutch retainer ring 52 has been replaced by a modified clutch retainerring 52'. The clutch ring 52' includes a first cylindrical ring portion52a of a diameter which permits it to seat against the under surface ofthe clutch wheel 40 as shown in FIG. 21, and a second cylindrical ringportion 52b of lesser diameter than the first ring portion 52a. Thereduced diameter ring portion 52b is integrally connected to the ringportion 52a by an annular transverse shoulder portion 52c and it extendscoaxially outwardly relative to the first ring portion 52a. The diameterof the ring portion 52b is selected so that the ring portion 52b fitsloosely inside of the flange 64 of the sleeve 62 and extends coaxiallybetween the coil spring 67 and spindle 16. As shown in FIG. 21, theouter end of the cylindrical ring portion 52b is normally spaced fromthe upper surface of the lip 69 of ground contact plunger 66 by adistance Z when the ground contact plunger is fully extended. However,when the ground contact plunger is forced upwardly within the hollowsleeve 62 upon impact of the cutter head 10' upon the ground or otherhard surface, the outer end of the ring 52' engages the top surface ofthe ground contact plunger lip 69 at the upper limit of movement of theground contact plunger 66 as seen in FIG. 22. The frictional contact ofthe ring 52' with the ground contact plunger 66 serves to transmitforces of relative rotary motion of the plunger 66 to the clutch wheel40, thereby aiding incremental indexing of the clutch wheel 40 andincremental feed of the filaments 88. The aforesaid assistance toincremental indexing of the clutch ring 52' becomes a critical factor inincremental feeding if the filament lines 88 are short or broken, androtational speed of the cutter head 10 is low, thereby producing reducedcentrifugal force for incremental feeding.

To further explain how the modified clutch retainer ring assists inincremental indexing of the clutch wheel, it will be recognized thatduring the cutting operation of the cutter head 10', the cutter head 10'will be rotating at a speed corresponding to the speed of rotationtransmitted to the spindle 16 by the drive means D illustrated in FIG.3. Rotary movement of the spindle 16 is transmitted to the filamentspindle 80 through the clutch key 38 and clutch wheel 40. Although theground contact plunger 66 is free to rotate relative to the spindle 16and clutch key 38 because the only connection of the plunger 66 to thespindle 16 is the sliding connection between tab 38c on the clutch key38 and the annular groove 72 on the inner face of the hollow plunger 66,the bias of the coil spring 67 on the inner end of the ground contactplunger normally results in sufficient frictional contact between theground contact plunger and rotating parts of the cutting head 10' tocause rotation of the plunger 66 therewith. However, when the groundcontact plunger is bumped upon the ground, frictional contact of theplunger 66 with the ground will momentarily slow or stop the rotation ofthe plunger 66 relative to the ground. The plunger 66, as a result ofthe bumping, is forced into the sleeve 62 to the limit of upward motionas shown in FIG. 22. Drag imparted to the clutch wheel 40 through theclutch retainer ring 52', which now has frictional contact with both theclutch wheel 40 and the plunger 66 assists in incremental indexing ofthe clutch wheel, and corresponding incremental feed of the filamentsbecause the speed of the clutch wheel 40 is slowed while the spindle 16continues to rotate at approximately the same speed. The filament spool80 which is keyed to the clutch wheel 40 shifts angular position duringincremental indexing relative to the posts 43 against which thefilaments 88 bear. Another incremental length of the filaments 88 isthereby permitted to be fed outwardly beyond the posts 43.

FIGS. 23 and 24 show the curved side surfaces of the clutch key elements138A and 138B of the clutch key 138 of cutter head 100 (FIG. 17). Theopposite side surfaces of the upper clutch key element 138A curveinwardly and downwardly to a common bottom edge while the opposite sidesurfaces of the lower clutch key element curve inwardly and upwardly toa common top edge as seen in FIG. 24. The curved side surfaces of theclutch key elements 138A and 138B provide smooth entry of the clutch keyelements into the top and bottom clutch cavities 140A and 140B of theclutch wheel 140 without excessive wear or chipping of the engagingsurfaces.

As seen in FIG. 20, the clutch wheel 140 of cutter head 100 differs fromthe clutch wheel 40 of cutter head 10. It has a radially extending upperflange 140c from which circumferentially spaced posts 141 depend. Theposts 141 are press fit into holes provided in the flange 140c, and theyslide easily into holes provided adjacent the inner periphery of thespool 180 (FIG. 17) to secure the clutch wheel 140 in assembledrelationship with the filament spool 180. The clutch wheel 140 withposts 141 thus provides another way for interlocking a clutch wheel witha filament spool.

While there have been shown and described particular embodiments of theinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made therein without departing from theinvention and, therefore, it is aimed to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A vegetation cuttingapparatus of the filament type comprising a cutter head including aspindle adapted to be rotatably driven, a keyway in said spindleextending axially of said spindle, a key member carried by said spindleand slidably movable in said keyway, a clutch means coaxially mounted onsaid spindle, a spool mounted on said spindle for storing the filament,at least one filament stored on said spool, said spool being carried byand lying radially outwardly of said clutch means whereby said clutchmeans and said spool rotatably move as a unit, means normally biasingsaid key member into driving engagement with said clutch means wherebynormally said spindle rotatably drives said clutch means through saidkey member to thereby rotatably drive said spool, means for impartingaxial movement to said key member along said keyway against said biasingmeans whereby to move said key member out of driving relation withrespect to said clutch means, and thus whereby to transitorily interruptthe rotatable drive connection from said spindle to said spool throughsaid clutch means, whereby to permit relative rotation between saidspool and said spindle, and thus whereby to permit an increment of saidfilament to be fed by centrifugal force from said spool.
 2. A vegetationcutting apparatus as defined in claim 1 in which said spool is easilydetachably keyed to said clutch means whereby to facilitate replacementand/or reloading of said spool.
 3. A vegetation cutting apparatus asdefined in claim 1 in which said clutch means comprises a firstplurality of circumferentially spaced upper clutch cavities and a secondplurality of circumferentially spaced lower clutch cavities axiallypositioned beneath said upper clutch cavities, and in which said keymember comprises first and second axially spaced key elements, saidfirst key element being normally biased into driving relation with acavity of one plurality of clutch cavities whereby to rotatably drivesaid clutch means and thus whereby to rotatably drive said spool, andwherein said axial movement imparted to said key member is effective totransitorily move said first key element out of driving relation with acavity of said one plurality and to move said second key element intodriving relation with a cavity of said second plurality, whereby torotatably drive said clutch means and thus whereby to rotatably drivesaid spool.
 4. A vegetation cutting apparatus as defined in claim 3 inwhich said first key element is normally biased into driving engagementwith a cavity of said first plurality defined by said upper clutchcavities.
 5. A vegetation cutting apparatus as defined in claim 3 inwhich said upper clutch cavities are circumferentially offset from saidlower clutch cavities by a predetermined percentage of a cavity pitch.6. A vegetation cutting apparatus as defined in claim 5 in which saidupper clutch cavities are circumferentially offset from said lowerclutch cavities by one-half pitch.
 7. A vegetation cutting apparatus asdefined in claim 1 in which said means for imparting axial movement tosaid key member is a ground contact plunger carried by the normallylower end of said cutter head, and means operatively interrelating saidground contact plunger and said key member.
 8. A vegetation cuttingapparatus as defined in claim 1 in which said means for imparting axialmovement to said key member is an operating rod, operativelyinterrelated with said key member and adapted to be actuated by a cableor the like to axially move said key member whereby to cause feeding ofan increment of said filament.
 9. A vegetation cutting apparatus asdefined in claim 1 in which a flyball governor is connected to said keymember to impart movement thereto in response to a predetermineddecrease in speed of rotation of said spindle, whereby to cause feedingof an increment of said filament.
 10. A vegetation cutting apparatus asdefined in claim 1 including vibration damping means carried by saidcutter head.
 11. A vegetation cutting apparatus as defined in claim 1including a plurality of circumferentially spaced axially extendingposts mounted on said cutter head, at least one of said posts beingpositioned in the path of circumferential swinging movement of afilament portion extending outwardly from said spool whereby to serve asan abutment limiting the circumferential swinging movement of saidportion of said filament.
 12. A vegetation cutting apparatus as definedin claim 1 including a hollow generally cylindrical cap member mountedon the normally upper portion of said spindle, said cap member extendingradially outwardly from said spindle in overlying relation to saidclutch member, to said spool, and to said key member; a plurality ofcircumferentially spaced posts mounted on said cap member, said postsincluding a first portion of the length thereof lying within the hollowinterior of said cap member and a second portion of the length thereofprojecting below said cap member and lying radially outwardly of saidspool member.
 13. A vegetation cutting apparatus as defined in claim 12including vibration damping means mounted on said first portion of thelength of said posts within said hollow interior of said cap member. 14.A vegetation cutting apparatus as defined in claim 13 in which saidvibration damping means comprise counterweights defined by metal washersor the like fitted loosely on said posts to provide a substantialclearance between the outer periphery of the respective posts and theinner periphery of the central apertures of said washers.
 15. Avegetation cutting apparatus as defined in claim 1 in which said cutterhead includes a cover plate lying beneath said spool, and meansdetachably securing said cover plate to said cutter head.
 16. Avegetation cutting apparatus as defined in claim 15 in which said coverplate is provided with saw teeth on the outer periphery thereof.
 17. Avegetation cutting apparatus of the filament type comprising a cutterhead including a spindle adapted to be rotatably driven, a keyway insaid spindle extending axially of said spindle, a key member carried bysaid spindle and slidably movable in said keyway, a clutch meanscoaxially mounted on said spindle, a spool mounted on said spindle forstoring the filament, at least one filament stored on said spool, saidspool being carried by and lying radially outwardly of said clutch meanswhereby said clutch means and said spool rotatably move as a unit, saidkey member being movable into driving engagement with said clutch meanswhereby normally said spindle rotatably drives said clutch means throughsaid key member to thereby rotatably drive said spool, a ground contactplunger carried by said spindle and engageable with the ground, saidground contact plunger being mounted for limited axial movement relativeto said spindle, means interrelating said key member and said groundcontact plunger whereby axial movement of said ground contact plunger isimparted to said key member, spring means biasing said ground contactplunger in a normally downward axial direction relative to said spindleto thereby also normally bias said key member in a downward directioninto driving engagement with said clutch member, whereby "bumping"movement of said ground contact plunger against the ground is effectiveto move said key member upwardly against the biasing force of saidspring means out of driving engagement with said clutch means, and thuswhereby to permit an increment of said filament to be fed by centrifugalforce from said spool.
 18. A vegetation cutting apparatus as defined inclaim 17 in which said spool is easily detachably keyed to said clutchmeans whereby to facilitate replacement and/or reloading of said spool.19. A vegetation cutting apparatus as defined in claim 17 in which saidmeans interrelating said key member and said ground contact plungercomprises a follower key element on said key member and an annulargroove on said ground contact plunger, said follower key element beingmounted in engagement with said annular groove whereby vertical movementimparted to said ground contact plunger due to "bumping" on the groundcauses corresponding vertical movement of said key member, and in whichthe mounting of said follower key element in said annular groove permitssaid ground contact plunger to slip or rotate independently of saidspindle when severe rotational impact forces are imparted to said groundcontact plunger.
 20. A vegetation cutting apparatus as defined in claim17 in which said ground contact plunger member is hollow for asubstantial portion of the interior thereof and is mounted for limitedtelescopic movement in an axial direction relative to said spindlemember when "bumping" of said ground contact plunger against the groundoccurs, and detent means carried by one of said members and engageablewith the other of said members to maintain said ground contact plungermember and said spindle member in detachably assembled relation to eachother during normal operation and also when said telescopic movementoccurs.
 21. A vegetation cutting apparatus as defined in claim 20 inwhich said detent means comprises a lateral plunger member received in alateral cavity in said spindle member, said lateral cavity extendingsubstantially perpendicularly to the normally vertical axis of saidspindle member, laterally extensible spring means positioned in saidlateral cavity and cooperating with said plunger member to bias aprojectible portion of said plunger member outwardly of said lateralcavity, and additional annular groove means in said ground contactplunger for receiving said projectable portion of said lateral plungermember whereby to retain said ground contact plunger assembled on saidspindle.
 22. A vegetation cutting apparatus as defined in claim 21 inwhich said lateral plunger member is retractable against the biasingforce of said laterally extensible spring means to retract saidprojectable portion of said plunger member into said lateral cavity insaid spindle member, whereby to withdraw said projectable portion ofsaid plunger member from engagement with said additional annular groovemeans of said ground contact plunger member, and thus whereby to permitsaid ground contact plunger member to be disassembled relative to saidspindle member.
 23. A vegetation cutting apparatus as defined in claim17 comprising a hollow cylindrical retaining sleeve positioned coaxiallyabout said spindle, said retaining sleeve being positioned about andreceiving on the interior thereof said axial biasing spring means, saidretaining sleeve receiving the upper portion of said ground contactplunger, said ground contact plunger lying axially beneath said axialbiasing spring means, said axial biasing spring means bearing at itsupper end against abutment means forming a part of said retainingsleeve, said axial biasing spring means bearing at its lower end againstsaid ground contact plunger, said axial biasing spring means exerting adownward axial biasing force on said ground contact plunger, and detentmeans detachably engaging said ground contact plunger with said spindlewhereby to retain said ground contact plunger detachably mounted on saidspindle member.
 24. A vegetation cutting apparatus as defined in claim23 in which said ground contact plunger is provided with a firstaperture extending radially through the wall thereof, and said hollowcylindrical retaining sleeve is provided with a second apertureextending radially through the wall thereof, said ground contact plungerand said cylindrical retaining sleeve being angularly adjustable aboutthe axis of said spindle whereby to radially align said first and saidsecond apertures with each other and with said lateral plunger membercarried by said spindle, whereby to permit retraction of said lateralplunger member against the force of said laterally extensible springmeans into said lateral cavity in said spindle, and thus whereby topermit disassembly of said ground contact plunger member relative tosaid spindle member.
 25. A vegetation cutting apparatus as defined inclaim 23 in which said cylindrical retaining sleeve is provided with atleast one abutment projecting radially outwardly from the outerperiphery of the outer cylindrical surface of said retaining sleeve,said retaining sleeve being angularly adjustable about the axis of saidspindle, an annular cover plate detachably mounted on said cutter headbeneath said spool in coaxial relation to said spindle, said cover platebeing provided on the inner periphery thereof with at least one apertureadapted to mate with and receive said abutment on the outer periphery ofsaid cylindrical sleeve, whereby to permit said cover plate to becoaxially positioned beneath the lower portion of said cylindricalsleeve with said abutment on said sleeve passing through said apertureon said cover plate during the assembly operation of said cover plate onsaid cutter head, and whereby subsequent to said assembly operation topermit said sleeve to be angularly adjusted to move said abutment onsaid sleeve out of registry with said aperture on said cover platewhereby to retain said cover plate in assembled relation relative tosaid cutter head.
 26. A vegetation cutting apparatus as defined in claim17 in which said cutter head includes a cover plate lying beneath saidspool, and means detachably securing said cover plate to said cutterhead.
 27. A vegetation cutting apparatus as defined in claim 26 in whichthe normally lower axial end surface of said spool abuts against thenormally upper surface of said cover plate, and said spring meansmaintains a constant pressure between said lower end surface of saidspool and said upper surface of said cover plate, whereby to provide adirt and mud seal at the interface between said surfaces.
 28. Avegetation cutting apparatus of the filament type comprising a cutterhead including a spindle adapted to be rotatably driven, a keyway insaid spindle extending axially of said spindle, a key member carried bysaid spindle and slidably movable in said keyway, a clutch meanscoaxially mounted on said spindle, a spool mounted on said spindle forstoring the filament, said spool being keyed to and lying radiallyoutwardly of said clutch means, means normally biasing said key memberinto driving engagement with said clutch means whereby normally saidspindle rotatably drives said clutch means through said key member tothereby rotatably drive said spool, means for imparting axial movementto said key member along said keyway against said biasing means wherebyto move said key member out of driving relation with respect to saidclutch means, and thus whereby to transitorily interrupt the rotatabledrive connection from said spindle to said spool through said clutchmeans whereby to permit an increment of said filament to be fed bycentrifugal force from said spool, and a circular cover plate mounted onsaid spindle beneath said spool, said cover plate being provided withsaw-like teeth on its outer periphery for cutting heavy growth ofvegetation.
 29. The vegetation cutting apparatus of claim 1 wherein saidspindle has an axial bore extending therethrough, and wherein said meansfor imparting axial movement to said key member includes a key operatingrod slidably mounted in said bore, and means interconnecting said keyoperating rod with said key member for transmitting axial slidingmovement of said key operating rod to axial movement of said key member,and means for imparting axial sliding movement to said key operatingrod.
 30. The vegetation cutting apparatus of claim 29 wherein said meansfor imparting axial sliding movement to said key operating rod comprisesa pull cord and means interconnecting said pull cord with said keyoperating rod whereby a pull applied to the pull cord will cause axialmovement of said key operating rod and of said key member against saidbiasing means.
 31. The vegetation cutting apparatus of claim 29 whereinsaid means for imparting axial movement of said key operating rodcomprises flyball governor means.
 32. The vegetation cutting apparatusof claim 29 wherein said means for imparting axial movement to saidoperating rod comprises a mass weight and means interconnecting saidmass weight with said key operating member whereby the inertia effect ofsaid mass weight in response to a sudden movement thereof will impartaxial sliding movement to said operating rod.